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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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 */

package javax.management.monitor;

import static com.sun.jmx.defaults.JmxProperties.MONITOR_LOGGER;

import java.util.logging.Level;
import javax.management.ObjectName;
import javax.management.MBeanNotificationInfo;

import static javax.management.monitor.MonitorNotification.*;

/**
 * Defines a monitor MBean designed to observe the values of a string
 * attribute.
 * <P>
 * A string monitor sends notifications as follows:
 * <UL>
 * <LI> if the attribute value matches the string to compare value,
 * a {@link MonitorNotification#STRING_TO_COMPARE_VALUE_MATCHED
 * match notification} is sent.
 * The notify match flag must be set to <CODE>true</CODE>.
 * <BR>Subsequent matchings of the string to compare values do not
 * cause further notifications unless
 * the attribute value differs from the string to compare value.
 * <LI> if the attribute value differs from the string to compare value,
 * a {@link MonitorNotification#STRING_TO_COMPARE_VALUE_DIFFERED
 * differ notification} is sent.
 * The notify differ flag must be set to <CODE>true</CODE>.
 * <BR>Subsequent differences from the string to compare value do
 * not cause further notifications unless
 * the attribute value matches the string to compare value.
 * </UL>
 *
 * @since 1.5
 */
public class StringMonitor extends Monitor implements StringMonitorMBean {

    /*
     * ------------------------------------------
     *  PACKAGE CLASSES
     * ------------------------------------------
     */

  static class StringMonitorObservedObject extends ObservedObject {

    public StringMonitorObservedObject(ObjectName observedObject) {
      super(observedObject);
    }

    public final synchronized int getStatus() {
      return status;
    }

    public final synchronized void setStatus(int status) {
      this.status = status;
    }

    private int status;
  }

    /*
     * ------------------------------------------
     *  PRIVATE VARIABLES
     * ------------------------------------------
     */

  /**
   * String to compare with the observed attribute.
   * <BR>The default value is an empty character sequence.
   */
  private String stringToCompare = "";

  /**
   * Flag indicating if the string monitor notifies when matching
   * the string to compare.
   * <BR>The default value is set to <CODE>false</CODE>.
   */
  private boolean notifyMatch = false;

  /**
   * Flag indicating if the string monitor notifies when differing
   * from the string to compare.
   * <BR>The default value is set to <CODE>false</CODE>.
   */
  private boolean notifyDiffer = false;

  private static final String[] types = {
      RUNTIME_ERROR,
      OBSERVED_OBJECT_ERROR,
      OBSERVED_ATTRIBUTE_ERROR,
      OBSERVED_ATTRIBUTE_TYPE_ERROR,
      STRING_TO_COMPARE_VALUE_MATCHED,
      STRING_TO_COMPARE_VALUE_DIFFERED
  };

  private static final MBeanNotificationInfo[] notifsInfo = {
      new MBeanNotificationInfo(
          types,
          "javax.management.monitor.MonitorNotification",
          "Notifications sent by the StringMonitor MBean")
  };

  // Flags needed to implement the matching/differing mechanism.
  //
  private static final int MATCHING = 0;
  private static final int DIFFERING = 1;
  private static final int MATCHING_OR_DIFFERING = 2;

    /*
     * ------------------------------------------
     *  CONSTRUCTORS
     * ------------------------------------------
     */

  /**
   * Default constructor.
   */
  public StringMonitor() {
  }

    /*
     * ------------------------------------------
     *  PUBLIC METHODS
     * ------------------------------------------
     */

  /**
   * Starts the string monitor.
   */
  public synchronized void start() {
    if (isActive()) {
      MONITOR_LOGGER.logp(Level.FINER, StringMonitor.class.getName(),
          "start", "the monitor is already active");
      return;
    }
    // Reset values.
    //
    for (ObservedObject o : observedObjects) {
      final StringMonitorObservedObject smo =
          (StringMonitorObservedObject) o;
      smo.setStatus(MATCHING_OR_DIFFERING);
    }
    doStart();
  }

  /**
   * Stops the string monitor.
   */
  public synchronized void stop() {
    doStop();
  }

  // GETTERS AND SETTERS
  //--------------------

  /**
   * Gets the derived gauge of the specified object, if this object is
   * contained in the set of observed MBeans, or <code>null</code> otherwise.
   *
   * @param object the name of the MBean whose derived gauge is required.
   * @return The derived gauge of the specified object.
   */
  @Override
  public synchronized String getDerivedGauge(ObjectName object) {
    return (String) super.getDerivedGauge(object);
  }

  /**
   * Gets the derived gauge timestamp of the specified object, if
   * this object is contained in the set of observed MBeans, or
   * <code>0</code> otherwise.
   *
   * @param object the name of the object whose derived gauge timestamp is to be returned.
   * @return The derived gauge timestamp of the specified object.
   */
  @Override
  public synchronized long getDerivedGaugeTimeStamp(ObjectName object) {
    return super.getDerivedGaugeTimeStamp(object);
  }

  /**
   * Returns the derived gauge of the first object in the set of
   * observed MBeans.
   *
   * @return The derived gauge.
   * @deprecated As of JMX 1.2, replaced by {@link #getDerivedGauge(ObjectName)}
   */
  @Deprecated
  public synchronized String getDerivedGauge() {
    if (observedObjects.isEmpty()) {
      return null;
    } else {
      return (String) observedObjects.get(0).getDerivedGauge();
    }
  }

  /**
   * Gets the derived gauge timestamp of the first object in the set
   * of observed MBeans.
   *
   * @return The derived gauge timestamp.
   * @deprecated As of JMX 1.2, replaced by {@link #getDerivedGaugeTimeStamp(ObjectName)}
   */
  @Deprecated
  public synchronized long getDerivedGaugeTimeStamp() {
    if (observedObjects.isEmpty()) {
      return 0;
    } else {
      return observedObjects.get(0).getDerivedGaugeTimeStamp();
    }
  }

  /**
   * Gets the string to compare with the observed attribute common
   * to all observed MBeans.
   *
   * @return The string value.
   * @see #setStringToCompare
   */
  public synchronized String getStringToCompare() {
    return stringToCompare;
  }

  /**
   * Sets the string to compare with the observed attribute common
   * to all observed MBeans.
   *
   * @param value The string value.
   * @throws IllegalArgumentException The specified string to compare is null.
   * @see #getStringToCompare
   */
  public synchronized void setStringToCompare(String value)
      throws IllegalArgumentException {

    if (value == null) {
      throw new IllegalArgumentException("Null string to compare");
    }

    if (stringToCompare.equals(value)) {
      return;
    }
    stringToCompare = value;

    // Reset values.
    //
    for (ObservedObject o : observedObjects) {
      final StringMonitorObservedObject smo =
          (StringMonitorObservedObject) o;
      smo.setStatus(MATCHING_OR_DIFFERING);
    }
  }

  /**
   * Gets the matching notification's on/off switch value common to
   * all observed MBeans.
   *
   * @return <CODE>true</CODE> if the string monitor notifies when matching the string to compare,
   * <CODE>false</CODE> otherwise.
   * @see #setNotifyMatch
   */
  public synchronized boolean getNotifyMatch() {
    return notifyMatch;
  }

  /**
   * Sets the matching notification's on/off switch value common to
   * all observed MBeans.
   *
   * @param value The matching notification's on/off switch value.
   * @see #getNotifyMatch
   */
  public synchronized void setNotifyMatch(boolean value) {
    if (notifyMatch == value) {
      return;
    }
    notifyMatch = value;
  }

  /**
   * Gets the differing notification's on/off switch value common to
   * all observed MBeans.
   *
   * @return <CODE>true</CODE> if the string monitor notifies when differing from the string to
   * compare, <CODE>false</CODE> otherwise.
   * @see #setNotifyDiffer
   */
  public synchronized boolean getNotifyDiffer() {
    return notifyDiffer;
  }

  /**
   * Sets the differing notification's on/off switch value common to
   * all observed MBeans.
   *
   * @param value The differing notification's on/off switch value.
   * @see #getNotifyDiffer
   */
  public synchronized void setNotifyDiffer(boolean value) {
    if (notifyDiffer == value) {
      return;
    }
    notifyDiffer = value;
  }

  /**
   * Returns a <CODE>NotificationInfo</CODE> object containing the name of
   * the Java class of the notification and the notification types sent by
   * the string monitor.
   */
  @Override
  public MBeanNotificationInfo[] getNotificationInfo() {
    return notifsInfo.clone();
  }

    /*
     * ------------------------------------------
     *  PACKAGE METHODS
     * ------------------------------------------
     */

  /**
   * Factory method for ObservedObject creation.
   *
   * @since 1.6
   */
  @Override
  ObservedObject createObservedObject(ObjectName object) {
    final StringMonitorObservedObject smo =
        new StringMonitorObservedObject(object);
    smo.setStatus(MATCHING_OR_DIFFERING);
    return smo;
  }

  /**
   * Check that the type of the supplied observed attribute
   * value is one of the value types supported by this monitor.
   */
  @Override
  synchronized boolean isComparableTypeValid(ObjectName object,
      String attribute,
      Comparable<?> value) {
    // Check that the observed attribute is of type "String".
    //
    if (value instanceof String) {
      return true;
    }
    return false;
  }

  @Override
  synchronized void onErrorNotification(MonitorNotification notification) {
    final StringMonitorObservedObject o = (StringMonitorObservedObject)
        getObservedObject(notification.getObservedObject());
    if (o == null) {
      return;
    }

    // Reset values.
    //
    o.setStatus(MATCHING_OR_DIFFERING);
  }

  @Override
  synchronized MonitorNotification buildAlarmNotification(
      ObjectName object,
      String attribute,
      Comparable<?> value) {
    String type = null;
    String msg = null;
    Object trigger = null;

    final StringMonitorObservedObject o =
        (StringMonitorObservedObject) getObservedObject(object);
    if (o == null) {
      return null;
    }

    // Send matching notification if notifyMatch is true.
    // Send differing notification if notifyDiffer is true.
    //
    if (o.getStatus() == MATCHING_OR_DIFFERING) {
      if (o.getDerivedGauge().equals(stringToCompare)) {
        if (notifyMatch) {
          type = STRING_TO_COMPARE_VALUE_MATCHED;
          msg = "";
          trigger = stringToCompare;
        }
        o.setStatus(DIFFERING);
      } else {
        if (notifyDiffer) {
          type = STRING_TO_COMPARE_VALUE_DIFFERED;
          msg = "";
          trigger = stringToCompare;
        }
        o.setStatus(MATCHING);
      }
    } else {
      if (o.getStatus() == MATCHING) {
        if (o.getDerivedGauge().equals(stringToCompare)) {
          if (notifyMatch) {
            type = STRING_TO_COMPARE_VALUE_MATCHED;
            msg = "";
            trigger = stringToCompare;
          }
          o.setStatus(DIFFERING);
        }
      } else if (o.getStatus() == DIFFERING) {
        if (!o.getDerivedGauge().equals(stringToCompare)) {
          if (notifyDiffer) {
            type = STRING_TO_COMPARE_VALUE_DIFFERED;
            msg = "";
            trigger = stringToCompare;
          }
          o.setStatus(MATCHING);
        }
      }
    }

    return new MonitorNotification(type,
        this,
        0,
        0,
        msg,
        null,
        null,
        null,
        trigger);
  }
}
